An activist investor has taken a stake in the industrial gases company.A high-profile activist investment firm has reportedly built a large stake in Air Products & Chemicals (APD 7.62%) and plans to push for changes at the industrial gas manufacturer. Investors are excited about the news, which came out Friday afternoon. As of 11 a.m. ET Monday, Air Products shares were up by 8% from Friday's close.Questions about succession, capital allocationAir Products distributes essential gases to industrial and medic ...